1. Field of the Invention
The present invention relates to a guard rail designed to ensure highway safety for automobiles on roads and to prevent them from leaving the road.
2. Description of Related Art
European Patent 0 184 525 teaches a guard rail formed by at least one horizontal rail composed of wooden rail elements and wooden posts, each post supporting two adjacent rail elements. Each element is provided at its ends with a metal armature or member enabling it to be connected to the adjacent end of an adjacent rail element.
In the first embodiment described in this European patent, the rail is mounted on the tops of posts and its elements are connected end to end by means of a T-shaped metal plate whose arms are inserted into the vertical and axial slots of two adjacent rail elements and whose lower part is inserted into a vertical slot provided in the upper end of the associated post. Assembly is provided by means of bolts passing completely through the post, the rail elements, and the plate. However, the T-shaped metal plate used in these embodiments requires relatively long and expensive manufacture.
According to an improved embodiment of the above rail, the subject of the first addition application 88 09037 to French Patent 84 17688, whose priority was claimed at the time the above European patent was filed, each metal armature or member is composed of at least one shaped metal strap with longitudinal edges curved to have a U-shaped cross section. One part is mounted on the periphery of the end of a rail element essentially parallel to the axis of the latter by means of at least one transverse bolt and on the periphery of the adjacent end of the adjacent rail element by means of at least one transverse bolt. While the curved longitudinal edges wedged into the ends of two successive rail elements give this plate an improved moment of inertia and consequently a better bending strength than a flat piece of iron, this improvement is limited by the fact that the height of the curved longitudinal edges must remain limited since they must enter the rail elements.